Alloy steel



Patented Feb. 14, 1928.

UNITED STATES PATENT OFFICE.

WILLIAM ROBERT SHIMEB AND ROY HAROLD CHRIST,

or na'raznanam, 2mm- ALLOY s'rnan.

Io Drawing. Application filed Kay 5,

This invention relates to alloy steels and it is somewhat similar from the standpoint of ingredients and from the standpoint of the method of manufacture to the inventions 5 of William Robert Shimer. disclosed and claimed in application Serial No. 752,929. filed November 29. 1924. and application Serial No. 28,219, filed May 5. 1925. both of .which are assigned to the Bethlehem Steel Company. We have discovered that. by low.-

ering the carbon range of the alloy disclosed in said applications. an alloy may be produced which is economical to manufacture. thereby making it available for a wide va- 1 riety of commercial uses. and which. at the same time. is endowed. with many desirable physical propeities.

The new alloy is strong and ductile: it

is capable of withstanding impact or repeated impact stresses in a highly satisfactory. manner; it is peculiarly suitable for case hardened articles; and it possesses the property of preserving its physical properties in v a high degree when heated. The object of our invention. therefore. is to produce an alloy having these desirable physical prop erties which" may be economically made. Our steel alloy consists essentially of tungsten and chromium with low percentagesof 80 carbon and manganese.

In preparing our alloy the fOllOWiUg may be used: scrap containing tungsten and chromium in suitable amounts. such as highspeed tool scrap. is added to an ordinary fur- 86 nace charge. the furnace being either of the open-hearth or electric type. but preferabl the former. pains being taken, to so control the charge and the operation of the furnace that the resultant alloy shall. not contain 40 too much manganese and shall. not-exceed 30% carbon. The high-speed tool scrap may be added to the normal charge at that time, either at the be innin ,or later. provided the addition talres p ate a s'nfiicient 46 time before tapping to secure melting ofthe scrap and alloying of the tungsten and of the chromium withthe metal of the bath. As already pointed out. charging of the furnace'is so regulated and the, furnace is so operated that the resultant alloy shall be low in carbon, for example. between .10 and and shall not contain too much mangases, for example, not more than 1.50%.

1925. Serial Ho. 28,218.

Too much manganese afiects the properties of toughness and ductility detrlmentally, that is, makes the alloy more brittle. Hence, in practice, we prefer to have the manganese content around 25% or 30%. The percenta e of tungsten and of chromium vary. 0? course, with the character and amounts of scrap added; and we have found that high speed tool scrap should be added in such amounts .as to secure in the resultant alloy chromium and tungsten each in amounts of from a fraction of 1% up to about 2 or 3%.

Our improved method of manufacture is not only economical from the standpoint of ingredients but also from the standpoint of more thorough incorporation of the tungsten and of the chromium in the metal of thebath. Ordinary alloy steel containing chromium and tungsten is produced by the addition of ferro-chrome' and tungsten, both of these ingredients being expensive. Also, due to its high specific gravity. it is impossible to alloy tungsten with iron without loss of tungsten. On the other hand, with our alloy. since the tool steel scrap already has the tungsten and chromium diluted in or alloyed with the iron and since there is very little difference in specific gravities between the scrap and the metal of the bath, the chromium and tungsten content of such scrap is wholly incorporated in the bath. While it would be possible to approximate our new alloy by the usual methods of incorporating ferro-chrome and tungsten, yet the cost would be so high that the field of use would necessarily be restricted. whereas. by our process, such an alloy may be produced at a cost but little more than low carbon steel.

Our new alloy, characterized by the low carbon range. the presence of chromium and tungsten, and not too much manganese is strong and ductile. Excellent case hardened articles may be made from it. The alloy possesses higher tensile and elastic limits than other carbon alloy steels. and it possesses a higher degree of ductility for increase in strength than the latter steels. Our alloy is highly resistant to impact stresses and repeated impact stresses, for example. for the Izod test the average for heat treated alloy steels is about 50 or foot pounds, whereas our alloy, as rolled and without any heat treatment is capable of standing a test of from 90 to 100 foot pounds.

If an ordinary piece of case hardened steel is broken, the fracture of the core will generally present a crystalline appearance, owing to the brittle character ofthe case. If our alloy is case hardened and tested in the same way, the core appears deep grey and silky, somewhat like the fracture of an ordinary piece of steel not case hardened. In other words, in the majority of breaks of ordinary case hardened steel, the fractures are crystalline, whereas, breaks of our case hardened alloy are not crystalline. This indicates that our case is hard with considerable toughness and ductility. It is, therefore, possible to make case hardened articles from our steel which are capable of withfrom ordinary case hardened steels.

The desirable aforementioned physical properties of our alloy and its characteristics of being economical from the standpoints of ingredients used and the process of manufacture make it suitable for the manufacture of a wide variety of articles, such as shafts, pistons, piston rods. valves, valve parts, crushers, and the like. In addition to these features we find that our alloy is capable of preserving its physical properties in good degree at high temperatures.

standing higher stresses than articles made This latter characteristic makes it suitable for the manufacture of articles used where high temperatures exist, for example, molds for cast iron or steel, structural members and parts used where high temperatures are obtained, and valves and the like subject to high temperatures.

Having thus described our invention What we claim as new and desire to secure by Letters Patent is:

1. A strong and ductile steel alloy capable of withstanding high impact stresses, containing as its essential constituents chromium and tungsten, each in appreciable amounts up to 2%, and carbon not in excess of 2. A strong and ductile steel alloy capable of withstanding high impact-stresses containing as its essential constituents chromium and tungsten, each in appreciable amounts up to 2%, carbon not in excess of .3070. and manganese not exceeding 1.50%.

3. An article of manufacture composed of a case hardened steel alloy, containing as its essential constituents chromium and tungsten, each in appreciable amounts up to 2%, and carbon not in excess of 30%.

In testimony whereof I hereunto signature this 1st day of May 1925.

IVILLIAM ROBERT SHIMER. In testimony whereof I hereunto alfix my signature this 1st day of May 1925.

ROY HAROLD CHRIST.

affix my 

